No abstract

The carboxylate ligand 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy)-based on the strongly fluorescent long-lifetime pyrene core-affords a permanently microporous fluorescent metal-organic framework, [In(2)(OH)(2)(TBAPy)].(guests) (1), displaying 54% total accessible volume and excellent thermal stability. Fluorescence studies reveal that both 1 and TBAPy display strong emission bands at 471 and 529 nm, respectively, upon excitation at 390 nm, with framework coordination of the TBAPy ligands significantly increasing the emission lifetime from 0.089 to 0.110 ms. Upon desolvation, the emission band for the framework is shifted to lower energy: however, upon re-exposure to DMF the as-made material is regenerated with reversible fluorescence behavior. Together with the lifetime, the emission intensity is strongly enhanced by spatial separation of the optically active ligand molecules within the MOF structure and is found to be dependent on the amount and chemical nature of the guest species in the pores. The quantum yield of the material is found to be 6.7% and, coupled with the fluorescence lifetime on the millisecond time scale, begins to approach the values observed for Eu(III)-cryptate-derived commercial sensors.

Porous materials find widespread application in storage, separation, and catalytic technologies. We report a crystalline porous solid with adaptable porosity, in which a simple dipeptide linker is arranged in a regular array by coordination to metal centers. Experiments reinforced by molecular dynamics simulations showed that low-energy torsions and displacements of the peptides enabled the available pore volume to evolve smoothly from zero as the guest loading increased. The observed cooperative feedback in sorption isotherms resembled the response of proteins undergoing conformational selection, suggesting an energy landscape similar to that required for protein folding. The flexible peptide linker was shown to play the pivotal role in changing the pore conformation

We report a methodology using machine learning to capture chemical intuition from a set of (partially) failed attempts to synthesize a metal-organic framework. We define chemical intuition as the collection of unwritten guidelines used by synthetic chemists to find the right synthesis conditions. As (partially) failed experiments usually remain unreported, we have reconstructed a typical track of failed experiments in a successful search for finding the optimal synthesis conditions that yields HKUST-1 with the highest surface area reported to date. We illustrate the importance of quantifying this chemical intuition for the synthesis of novel materials.

The present review showcases the scientific progress in the field of dual-functional photocatalysis for hydrogen evolution coupled with the oxidation of chemical substances. Considering that hydrogen is a promising alternative to fossil fuels, photocatalytic water splitting represents an approach to produce hydrogen using abundant solar energy. However, the industrialization of this process has not occurred yet, mainly due to limitations related to the high cost, toxicity, poor stability, or low efficiency of the majority of the photocatalytic systems employed for water reduction. An approach to tackle these limitations is by taking advantage of the oxidative energy of the holes and by replacing the expensive and often toxic sacrificial electron donors with either organic pollutants (targeting their degradation) or organic substances that can be oxidized to added-value products. Following this 2-fold strategy, the production of sustainable hydrogen is accompanied by either the oxidative degradation of pollutants or the valorization of organic processes, in a single process. Herein, a detailed overview of the advancements in this dual-purpose field is offered, along with a discussion of the basic principles, the differences between similar fields, and how these can be distinguished. Although in its infancy, this dual-purpose technology has received radically increasing scientific interest over the past few years; this is expected, as the utilization of this approach can overcome multiple major environmental challenges, such as global warming, water scarcity, and pollution.

Two new three-dimensional porous Zn(II)based metal−organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal−ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal−organic frameworks (MOFs) possess comparable BET surface areas and CO 2 uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO 2 compared to the network with onedimensional and relatively large poresattributable to the more effective interactions with the azine groups.

A stable donor–acceptor coordination complex of the elusive parent inorganic iminoborane HBNH (a structural analogue of acetylene) is reported. This species was generated via thermally induced N2 elimination/1,2‐H migration from a hydrido(azido)borane adduct NHC⋅BH2N3 (NHC=N‐heterocyclic carbene) in the presence of a fluorinated triarylborane. The mechanism of this process was also investigated by computational and isotopic labeling studies. This transformation represents a new and potentially modular route to unsaturated inorganic building blocks for advanced material synthesis.

Iodine (I 2 ) capture and recovery is an important process in many industrial practices. Conventional materials for I 2 capture include Ag 0 -based aerogels and zeolites and C-based aerogels and powders, which suffer from expensive and/or inefficient recovery. Recently, metal-organic frameworks (MOFs) have shown potential as good adsorbents for I 2 capture with high capacity, fast uptake, and good recyclability. The powder form of MOFs, however, often makes them impractical in large-scale applications. Herein, a versatile method based on the phase inversion technique is presented to fabricate millimetersized spherical MOF@polymer composite beads, and the use of these beads for I 2 capture and recovery is demonstrated. Besides preserving the crystallinity and pore accessibility of the embedded MOFs in the polymeric matrix, the beads exhibit higher capacity and faster uptake rate for I 2 in both vapor and liquid phases compared to the bulk MOF powder. In order to showcase the applicability of these beads, a gas-sparged column is used as a proof-ofconcept device that can efficiently capture and recover more than 99% of I 2 from the feeding solution. The beads can be recycled and reused multiple times, which in combination with their easy handling and storage highlights their superiority compared to MOF powders in adsorption applications.